Tooth-crown.



. HAEFER.

H GROWN.

APPLICATION FILED SEPT. 10, 1909.

959,2795. Patented May 24, 1910.

WITNESSES INVENTOR 26/ PaaB/yl'ne Jc/mefgr% ATTORNE Y8 PAULINE SCHAEFER, OF OAKLAND, CAI JIFOBNIA.

TOOTH-CROWN.

Specification of Letters Patent;

Patented May 24:, 1910.

Application filed September 10, 1909. Serial No. 517,016.

To all whom it may concern:

Be it known that I, PAULINE SOHAEFER, a citizen of the United States, and a resident of Oakland, in the county of Alameda and State of California, have invented a new and Improved Tooth-Crown, of which the following is a full, clear, and exact description.

This invention relates to certain improvements in tooth crowns, and more particularly to certain improvements in the manufacture of the pattern or model in imitation of which the gold crown is cast.

In forming a crown in accordance with my invention, I provide a band of comparatively stifi' material, which is combustible without leaving any ash and fit this band around the tooth near the base or root of the latter. The band is preferably made of celluloid and may be manufactured of various different sizes to fit difi'erent teeth. After the band is fitted to the tooth, it is filled with wax and the wax is molded to the form of the desired tooth. The band and wax are then removed together and used as a attern for the manufacture of a laster mo d. When the plaster is hardened it is heated and the wax either melts or burns out, while the celluloid burns out leaving no ash. Molten gold or other metal or alloy may be poured in and the resulting casting will have the form of both the wax body portion of the tooth and the celluloid band for encircling the tooth. The band portion of the crown is of uniform thickness, which would not be possible Were wax employed in forming the band portion of the pattern. Furthermore, the celluloid band gives the pattern the desired rigidity and enables it to be handled without distortion.

Reference is to be had to the accompanying drawings, forming a part of this specification, in which similar characters of reference indicate corresponding parts in all the figures, and in wh1ch Figure 1 is a perspective view of a band for use in making crowns in accordance with my invention; Fig. 2 is a perspective view showing in section, a band applied to a broken tooth; Fig. 3 is a perspective view showing the wax filling in the band and molded to the form of the tooth; Fig. 4. is a perspective view of the pattern after removal from the root; Fig. 5 is a vertical section through a mold formed about the pattern; and Fig. 6 is a vertical section through the mold after the removal of the pattern and prior to the casting of the complete metal crown.

The most important feature in the construction of crowns in accordance with my invention, is the use of a band 10 of substantially the form shown in Fig. 1, and of such size and proportions that it may be fitted about the exposed portion of a tooth closely adjacent the gum. The band is preferably formed of celluloid, although it is evident that in place of the celluloid I might use any similar suitable material which is completely combustible and which has sufficient rigidity to retain its form. After the band is fitted in place, it is filled with wax 11,and this wax is molded so that its exterior surface coincides with the desired crown. It is evident that in place of the wax, I might use any material which will readily melt under the influence of heat, or which may be readily burned out of the mold. Upon the completion of the model or pattern formed of the band and plastic filling, the pattern is removed and a short stem, pin or rod 12 is inserted in the top of the filling to constitute a handle and a support for the pattern, substantially as illustrated in Fig. 4. I then take a suitable base or block 13 and insert the end of the pin 12 therein, so as to support the pattern, as illustrated in Fig.5. A shell 14 is placed around the pattern and upon the base, and the shell is filled with a plastic self-hardening material 15, which maybe plaster of paris, and which forms the mold. Preferably, the base 13 has the upper surface thereof convex and the pin 12 extends up from the highest point, so that when the mold is thoroughly hardened and is removed from the base and inverted, it will have a funnel-shaped top 16. The pin 12 is then removed to leave a passage 17 and the mold is heated or baked to melt out or consume the wax and to entirely consume A tooth crown formed in this manner, conforms perfectly to the tooth, as an annular band for fitting around the tooth presents the desired-contour and is all formed 5 of a single casting.

Having thus described my invention, I claim as new and desire to secure by Letters Patent:

l. A attern for use in the manufacture 10 of metallic tooth crowns, having a combustible band portion and a plastic body portion.

2. A pattern for use in the manufacture of metallic tooth crowns, having a celluloid band lportion, and a plastic body portion. 15

3. fiattern for use in the manufacture of meta ic tooth crowns, having a celluloid band portion and a wax body portion.

In testimony whereof I have signed my name to this specification in the presence of 20 two subscribing witnesses.

PAULINE SGHAEFER.

Witnesses:

L. O. LEET, E. B. MCAULIFFE. 

